<!doctype html>
<html lang="en">

<head>
  <meta charset="utf-8">
  <title>Grid</title>
  <style>
      body {
        background: #fff;
    }
    .r {background: red; width: 300px; height: 50px}
    .g {background: green; width: 300px; height: 50px}
  </style>
</head>

<body>
        <div class=r></div>
        <div class=g></div>
        <div class=r></div>
        <div class=g></div>
        <div class=r></div>
        <div class=g></div>
</body>
</html>
